The point at which a hammer hit a flint, and struck the flake from a core is called the point of impact or percussion. The energy dissipated from this point, in a cone-like manner, which left a bulb of percussion on the ventral surface below the point of impact. Sometimes, it also leaves a small scar on the bulb, called the erailleur scar or bulbar scar. The impact can also leave small splits or fissures radiating away from the point of impact. Finally, the impact often leaves ripples fanning away from the bulb - this flake doesnt have fissures or ripples, but you will notice them on some of the following examples in this gallery.

The flake was struck off from a prepared flint core. part of the core striking platform remains on the proximal (striking) end of the flake as the butt.

Flakes can be struck either by a hard hammer (a hammerstone), or by soft hammer (antler, or bone punches). A hard hammer creates larger bulbar scars, prominent ripples, and hinge fractures - it is less controlled, and creates a more curved squatter flake. Striking a flake further into a striking platform with a hard hammer, creates thicker flakes - suitable for retouching into scrapers. Skilled use of a soft hammer can create flatter longer flakes with a flat sharp distal end. Using a specially prepared flint core, soft hammers, and indirect percussion (striking flint via a punch), a skilled knapper can create long thin slim flakes with parallel sides termed blades.